It's just a nice greeting to say. But if you don't want me to address with a starting "Hey" I suppose I won't.

Now, when it comes to Arena, the only stat line that carries over is initiative, for good reason considering it's what the system can generalize who goes first. Outside of that, it's a fair battleground. Since you're asking for my personal statement, I'll provide it.
If there are teams with a premium ninja that's becoming a nuisance, form a counter team. Considering how they're not at their own BP against you, you can actually survive. So build defensively, or try something new.

We can't do anything about Ninjas and how they're used. It's the right of the players to use whatever they see fit (in terms of characters) from silly teams to serious competitive teams. It's up to you guys.

If you have any additional things, feel free to message me.